ADRENERGIC MECHANISM IN HYPERKETONEMIA IN THYROTOXIC AND STARVED RATS

To evaluate the possible role of the adrenergic mechanism in hyperketo nemia in hyperthyroidism and starvation, the plasma concentrations of FFA, acetoacetate (AcAc), and beta-hydroxybutyrate (BOHB) were measure d in thyrotoxic and starved rats for 96 hours. Thyrotoxemia was induce d in rats by a daily subcutaneous thyroxine (100 mug/kg/day) injection carried out for 7 days. Some of the thyrotoxic and starved rats were administered subcutaneous phentolamine (2 mg/kg, twice daily) or propr anolol (0.1 mg/kg, twice daily). Plasma levels of FFA, AcAc, and BOHB were significantly increased in thyrotoxic and starved rats compared w ith the control rats. Phentolamine and propranolol administration did not alter plasma levels of FFA, AcAc, and BOHB in thyrotoxic rats. In starved rats, propanolol did not alter plasma levels of FFA, AcAc, and BOHB, however, phentolamine did increase plasma levels of FFA, AcAc, and BOHB. These results indicate that the adrenergic mechanism may not contribute to the hyperketonemia in thyrotoxic rats, but may have a s light inhibitory effect on ketogenesis in starvation probably due to a lpha-antilipolytic action.